In many industrial manufacturing apparatuses such as wafer table or mask table in the lithography machine, a workpiece or workpiece table is required to perform a multiple-degree-of-freedom motion while being precisely positioned. In order to enable the multiple-degree-of-freedom motion and precise positioning, a drive motor may be used to directly provide the support, such that, however, the load of the drive motor is increased and so the heating of the motor is increased. In many workpiece tables of ultraprecision, the heat generated by the drive motor may influence the temperature of the atmosphere to generate a non-contact type error in measurement which may finally influence the precision of positioning. However, a gravity compensating structure can reduce the load and heating of the motor.
The non-contact type gravity compensating structure of permanent magnet has advantages. Its structure is simple and precise processing of the surface of parts or components is not required, and it can be applied in a vacuum atmosphere. However, for such non-contact type gravity compensating structure of permanent magnet, a small stiffness and large bearing capacity in the direction of axis is required between the fixing part and the supporting part. With the development of magslev workpiece table, the large-stroke motion stage of the magslev workpiece table has a large array of halbach magnetic steel to generate a strong magnetic field which may have a large influence on the gravity balancing of the rotor of the micropositioner in operation.